This invention relates to water pumps for internal combustion engines, including but not limited to, water pump impellers.
Internal combustion engines typically include a water pump having a pump chamber, and an impeller on a rotating shaft that extends through the pump chamber. A seal assembly within the water pump housing may include two seal faces, which may be of carbon, silicon carbide, or ceramic face material. The mating face rotates with the shaft, and the seal face is pressed into a bearing housing and does not rotate. Absent coolant circulation about the seal, the coolant adjacent to and in between the seal faces becomes hot, boils, and vaporizes, causing residue to be deposited on the face. This residue reduces the seal""s ability to retain the liquid in the pump chamber. If lack of coolant circulation about the seal persists, the seal chamber becomes dry and overheated, causing the seal to fail.
High temperature environments at the seal face reduce the life of the seal and necessitate early replacement of the water pump. Extending the life of a seal is desirable to reduce maintenance expenses of engines. Proper water pump function is important to maintain basic engine operation.
Methods and assemblies that reduce heat build up at the seal have been proposed. These approaches introduce complex assembly and manufacturing operations and add cost to the overall engine. Examples of these approaches are found in U.S. Pat. Nos. 5,827,041 and 6,079,942. The U.S. Pat. No. 5,827,041 patent describes a water pump having a shrouded chamber around the seal. Fluid channels are machined in the housing to direct coolant flow to the area around the seal for transfer of heat dissipated by the seal. The added components of the seal shroud and the manufacturing operations forming the fluid channels increase the complexity and cost of the water pump. The U.S. Pat. No. 6,079,942 patent introduces an additional flushing ring to circulate the fluid evenly around the seal. The flushing ring introduces additional components and manufacturing and assembly costs to the water pump.
Accordingly, there is a need for an apparatus for reducing heat build-up around a seal for a water pump without significantly increasing the complexity and cost of the water pump.
The invention provides a simple and inexpensive apparatus to provide a sufficient flow of coolant over and around a water pump seal to cool and lubricate the seal and thereby extend the life of the seal. A fluid path through the impeller directs coolant from a high pressure area of the pump near the outer periphery of the impeller and through the body of the impeller to a seal cavity proximate the seal. The coolant is drawn from the seal cavity through the impeller at the hub proximate the seal to return the coolant to the low pressure area of the pump. In a preferred embodiment, holes are provided in the impeller respectively adjacent the periphery and adjacent the drive shaft to provide a cooling circuit including the seal cavity.